Chapter 7: IP Addressingvapenik.s.cnl.sk/pcsiete/CCNA1/07_IP_Addressing.pdf · Cisco Confidential 2...

Chapter 7: IP Addressing

CCNA Routing and Switching

Introduction to Networks v6.0

7.1 IPv4 Network Addresses

Explain the use of IPv4 addresses to provide connectivity in small to medium-sized business networks

• Convert between binary and decimal numbering systems.

• Describe the structure of an IPv4 address including the network portion, the host portion, and the subnet

• Compare the characteristics and uses of the unicast, broadcast and multicast IPv4 addresses.

• Explain public, private, and reserved IPv4 addresses.

Configure IPv6 addresses to provide connectivity in small to medium-sized business networks.

• Explain the need for IPv6 addressing.

• Describe the representation of an IPv6 address.

• Compare types of IPv6 network addresses.

• Configure global unicast addresses.

• Describe multicast addresses.

Chapter 7 - Sections & Objectives

7.3 Connectivity Verification

Use common testing utilities to verify and test network connectivity.

• Explain how ICMP is used to test network connectivity.

• Use ping and traceroute utilities to test network connectivity.

Chapter 7 - Sections & Objectives (Cont.)

Binary numbering system consists of the numbers 0 and 1 called bits

• IPv4 addresses are expressed in 32 binary bits divided into 4 8-bit octets

Binary and Decimal Conversion

IPv4 Addresses

IPv4 addresses are commonly expressed in dotted decimal notation

IPv4 Addresses (Cont.)

The first row identifies the number base

or radix. Decimal is 10. Binary is based

on 2, therefore radix will be 2

The 2nd row considers the position of

the number starting with 0. These

numbers also represent the exponential

value that will be used to calculate the

positional value (4th row).

The 3rd row calculates the positional

value by taking the radix and raising it

by the exponential value of its position.

Note: n^0 is always = 1.

The positional value is listed in the

fourth row.

Positional Notation

Applying decimal positional notation

Positional Notation (Cont.)

Applying binary positional notation.

To convert a binary IPv4 address to decimal enter the 8-bit binary number of each octet under the

positional value of row 1 and then calculate to produce the decimal.

Binary to Decimal Conversion

To convert a decimal IPv4address

to binary use the positional chart

and check first if the number is

greater than the 128 bit. If no a 0 is

placed in this position. If yes then a

1 is placed in this position.

128 is subtracted from the original

number and the remainder is then

checked against the next position

(64) If it is less than 64 a 0 is placed

in this position. If it is greater, a 1 is

placed in this position and 64 is

subtracted.

The process repeats until all

positional values have been

entered.

Decimal to Binary Conversion

Decimal to Binary Conversion Examples

An IPv4 address is hierarchical.

• Composed of a Network portion

and Host portion.

All devices on the same network

must have the identical network

portion.

The Subnet Mask helps devices

identify the network portion and

host portion.

IPv4 Address Structure

Network and Host Portions

Three IPv4 addresses must be

configured on a host:

• Unique IPv4 address of the host.

• Subnet mask - identifies the

network/host portion of the IPv4

address.

• Default gateway -IP address of the

local router interface.

The Subnet Mask

The Subnet Mask (Cont.)

The IPv4 address is compared to the subnet mask bit by bit, from left to right.

A 1 in the subnet mask indicates that the corresponding bit in the IPv4 address is a

network bit.

Logical AND

A logical AND is one of three

basic binary operations used in

digital logic.

Used to determine the Network

Address

The Logical AND of two bits yields

the following results:

The Prefix Length

The Prefix Length:

• Shorthand method of

expressing the subnet mask.

• Equals the number of bits in

the subnet mask set to 1.

• Written in slash notation, /

followed by the number of

network bits.

Network, Host, and Broadcast Addresses

Types of Addresses in Network

192.168.10.0/24

• Network Address - host portion is all 0s

(.00000000)

• First Host address - host portion is all 0s

and ends with a 1 (.00000001)

• Last Host address - host portion is all 1s

and ends with a 0 (.11111110)

• Broadcast Address - host portion is all

1s (.11111111)

IPv4 Unicast, Broadcast, and Multicast

Static IPv4 Address Assignment to a Host

Some devices like printers, servers

and network devices require a fixed

IP address.

Hosts in a small network can also be

configured with static addresses.

Dynamic IPv4 Address Assignment to a Host

Most networks use Dynamic Host

Configuration Protocol (DHCP) to

assign IPv4 addresses dynamically.

The DHCP server provides an IPv4

address, subnet mask, default

gateway, and other configuration

information.

DHCP leases the addresses to hosts

for a certain length of time.

If the host is powered down or taken

off the network, the address is

returned to the pool for reuse.

IPv4 Communication

Unicast – one to one

communication.

Broadcast– one to

Multicast – one to a

select group.

Unicast Transmission

Unicast – one to one

communication.

• Use the address of the

destination device as the

destination address.

Broadcast Transmission

Broadcast– one to all

• Message sent to everyone in the LAN (broadcast domain.)

• destination IPv4 address has all ones (1s) in the host portion.

Multicast Transmission

Multicast– one to a select group.

• 224.0.0.0 to 239.255.255.255 addresses reserved for multicast.

• routing protocols use multicast transmission to exchange routing information.

Types of IPv4 Addresses

Public and Private IPv4 Addresses

Private Addresses

• Not routable

• Introduced in mid 1990s due to depletion of IPv4

addresses

• Used only in internal networks.

• Must be translated to a public IPv4 to be routable.

• Defined by RFC 1918

Private Address Blocks

• 10.0.0.0 /8 or 10.0.0.0 to 10.255.255.255

• 172.16.0.0 /12 or 172.16.0.0 to

172.31.255.255192.168.0.0 /16

• 192.168.0.0 to 192.168.255.255

Special User IPv4 Addresses

Loopback addresses (127.0.0.0 /8 or

127.0.0.1)

• Used on a host to test if the TCP/IP

configuration is operational.

Link-Local addresses (169.254.0.0 /16 or

169.254.0.1)

• Commonly known as Automatic Private IP

Addressing (APIPA) addresses.

• Used by Windows client to self configure if no

DHCP server available.

TEST-NET addresses (192.0.2.0/24 or 192.0.2.0 to

192.0.2.255)

• Used for teaching and learning.

Legacy Classful Addressing

In 1981, Internet IPv4 addresses were

assigned using classful addressing (RFC 790)

Network addresses were based on 3 classes:

• Class A (0.0.0.0/8 to 127.0.0.0/8) – Designed to

support extremely large networks with more than

16 million host addresses.

• Class B (128.0.0.0 /16 – 191.255.0.0 /16) –

Designed to support the needs of moderate to

large size networks up to approximately 65,000

host addresses.

• Class C (192.0.0.0 /24 – 223.255.255.0 /24) –

Designed to support small networks with a

maximum of 254 hosts.

Classless Addressing

Classful Addressing wasted addresses

and exhausted the availability of IPv4

addresses.

Classless Addressing Introduced in the

• Classless Inter-Domain Routing (CIDR,

pronounced “cider”)

• Allowed service providers to allocate IPv4

addresses on any address bit boundary

(prefix length) instead of only by a class A,

B, or C.

Assignment of IP Addresses

The following organizations manage and

maintain IPv4 and IPv6 addresses for the

various regions.

• American Registry for Internet Numbers

(ARIN)- North America.

• Réseaux IP Europeans (RIPE) - Europe, the

Middle East, and Central Asia

• Asia Pacific Network Information Centre

(APNIC) - Asia and Pacific regions

• African Network Information Centre (AfriNIC) –

Africa

• Regional Latin-American and Caribbean IP

Address Registry (LACNIC) - Latin America

and some Caribbean islands

IPv4 Issues

The Need for IPv6

IPv6 versus IPv4:

• Has a larger 128-bit address space

• 340 undecillion addresses

• Solves limitations with IPv4

• Adds enhancement like address auto-

configuration.

Why IPv6 is needed:

• Rapidly increasing Internet

population

• Depletion of IPv4

• Issues with NAT

• Internet of Things

IPv4 Issues

IPv4 and IPv6 Coexistence

Migration from IPv4 to IPv6 Techniques

Translation - Network

Address Translation 64

(NAT64) allows IPv6-enabled

devices to communicate with

IPv4 devices.

Tunneling - The IPv6

packet is encapsulated

inside an IPv4 packet.

Dual stack - Devices

run both IPv4 and IPv6

protocol stacks

simultaneously.

IPv6 Addressing

IPv6 Address Representation

IPv6 Addresses:

• 128 bits in length

• Every 4 bits is represented by a

single hexadecimal digit

• Hextet - unofficial term referring to a

segment of 16 bits or four

hexadecimal values.

IPv6 Addressing

IPv6 Address Representation (Cont.)

Preferred format for IPv6 representation

IPv6 Addressing

Rule 1 – Omit Leading 0s

In order to reduce or compress IPv6

• First rule is to omit leading zeros in any hextet.

IPv6 Addressing

Rule 2 – Omit All 0 Segments

• A double colon (::) can replace any single, contiguous

string of one or more 16-bit segments (hextets) consisting

of all 0s.

IPv6 Addressing

Rule 2 – Omit All 0 Segments (Cont.)

Rule 2 – Omit All 0 Segments

• A double colon (::) can replace any single, contiguous

string of one or more 16-bit segments (hextets) consisting

of all 0s.

IPv6 Address Types

Three types of IPv6 addresses:

• Unicast- Single source IPv6

address.

• Multicast - An IPv6 multicast

address is used to send a single

IPv6 packet to multiple destinations.

• Anycast - An IPv6 anycast address

is any IPv6 unicast address that can

be assigned to multiple devices.

IPv6 Prefix Length

The IPv6 prefix length is used to indicate the network portion of an IPv6 address:

• The prefix length can range from 0 to 128.

• Typical IPv6 prefix length for most LANs is /64

IPv6 Unicast Addresses

Global Unicast - These are

globally unique, Internet

routable addresses.

Link-local - used to

communicate with other

devices on the same local

link. Confined to a single

Unique Local - used for

local addressing within a site

or between a limited number

of sites.

IPv6 Link-Local Unicast Addresses

IPv6 link-local addresses:

• Enable a device to communicate

with other IPv6-enabled devices

on the same link only.

• Are created even if the device

has not been assigned a global

unicast IPv6 address.

• Are in the FE80::/10 range.

Note: Typically, it is the link-local address

of the router that is used as the default

gateway for other devices on the link.

Structure of an IPv6 Global Unicast Address

A global unicast address has

three parts:

• Global routing prefix - network,

portion of the address that is

assigned by the provider.

Typically /48.

• Subnet ID – Used to subnet

within an organization.

• Interface ID - equivalent to the

host portion of an IPv4 address.

Currently, only global unicast

addresses with the first three

bits of 001 or 2000::/3 are being

assigned

Static Configuration of a Global Unicast Address

Router Configuration:

Similar commands to IPv4,

replace IPv4 with IPv6

Command to configure andIPv6

global unicast on an interface is

ipv6 address ipv6-

address/prefix-length

Static Configuration of a Global Unicast Address (Cont.)

Host Configuration:

• Manually configuring the IPv6 address

on a host is similar to configuring an

IPv4 address

• Default gateway address can be

configured to match the link-local or

global unicast address of the Gigabit

Ethernet interface.

Dynamic assignment of IPv6

addresses:

• Stateless Address Autoconfiguration

(SLAAC)

• Stateful DHCPv6

Dynamic Configuration - SLAAC

Stateless Address

Autoconfiguration (SLAAC):

• A device can obtain its prefix, prefix

length, default gateway address,

and other information from an IPv6

router.

• Uses the local router’s ICMPv6

Router Advertisement (RA)

messages

ICMPv6 RA messages sent every

200 seconds to all IPv6-enabled

devices on the network.

Option 1 (SLAAC Only) – "I'm everything you need (Prefix,

Prefix-length, Default Gateway)"

Option 2 (SLAAC and DHCPv6) – "Here is my information

but you need to get other information such as DNS

addresses from a DHCPv6 server."

Option 3 (DHCPv6 Only) – "I can’t help you. Ask a DHCPv6

server for all your information."

Dynamic Configuration – DHCPv6

The RA Option 1: SLAAC only (this is

the default)

RA Option 2: SLAAC and Stateless

DHCPv6:

• Uses SLAAC for IPv6 global unicast

address and default gateway.

• Uses a stateless DHCPv6 server for other

information.

RA Option 3: Stateful DHCPv6

• Uses the Routers link-local address for

the default gateway.

• Uses DHCPv6 for all other information.

EUI-64 Process and Randomly Generated

When the RA message is SLAAC or

SLAAC with stateless DHCPv6, the client

must generate its own Interface ID

• The Interface ID can be created using the

EUI-64 process or a randomly generated 64-

bit number

An EUI-64 Interface ID is represented in

binary and is made up of three parts:

• 24-bit OUI from the client MAC address, but

the 7th bit (the Universally/Locally (U/L) bit)

is reversed.

• The inserted 16-bit value FFFE (in

hexadecimal).

• 24-bit Device Identifier from the client MAC

address.

EUI-64 Process and Randomly Generated (Cont.)

Randomly Generated Interface IDs

• Windows uses a randomly generated Interface ID

Dynamic Link-Local Addresses

Link-local address can be established dynamically or configured manually.

Cisco IOS routers use EUI-64 to generate the Interface ID for all link-local address on IPv6

interfaces.

Drawback to using the dynamically assigned link-local address is the long interface ID, therefore

they are often configured statically.

Static Link-Local Addresses

Manual Configuration of the link-local address allows the creation of a simple, easy to

remember address.

Verifying IPv6 Address Configuration

The commands to verify IPv6 configuration are similar to IPv4

• show ipv6 interface brief

• show ipv6 route

The ping command for IPv6 is identical to the command used with IPv4, except that

an IPv6 address is used.

IPv6 Multicast Addresses

Assigned IPv6 Multicast Addresses

There are two types of IPv6 multicast

addresses:

• Assigned multicast - reserved multicast

addresses for predefined groups of devices

• Solicited node multicast

Two common IPv6 assigned multicast

groups:

• FF02::1 All-nodes multicast group – This is

a multicast group that all IPv6-enabled

devices join. Similar to a broadcast in IPv4

• FF02::2 All-routers multicast group – This is

a multicast group that all IPv6 routers join.

IPv6 Multicast Addresses

Solicited-Node IPv6 Multicast Addresses

Solicited-node multicast address:

• Mapped to .a special Ethernet multicast address

• Allows Ethernet NIC to filter frame on destination

7.3 Connectivity Verification

ICMPv4 and ICMPv6

ICMPv4 is the messaging protocol for

IPv4. ICMPv6 provides the same

services for IPv6

ICMP messages common to both

include:

• Host confirmation

• Destination or Service Unreachable

• Time exceeded

• Route redirection

ICMPv6 Router Solicitation and Router Advertisement Messages

ICMPv6 includes four new protocols as part

of the Neighbor Discovery Protocol (ND or

• Router Solicitation (RS) message

• Router Advertisement (RA) message

RA messages used to provide addressing

information to hosts

• Neighbor Solicitation (NS) message

• Neighbor Advertisement (NA) message

Neighbor Solicitation and Neighbor

Advertisement messages are used for

Address resolution and Duplicate Address

Detection (DAD).

Testing and Verification

Ping - Testing the Local Stack

Ping the local loopback address of

127.0.0.1 for IPv4 or ::1 for IPv6 to

verify that IP is properly installed on the

Ping – Testing Connectivity to the Local LAN

Use ping to test the ability of a host

to communicate on the local

network.

Ping – Testing Connectivity to a Remote Host

Use ping to test the ability of a host

to communicate across an

internetwork.

Traceroute – Testing the Path

Traceroute (tracert) is a utility that

generates a list of hops that were

successfully reached along the path.

• Round Trip Time (RTT) – Time it takes

the packet to reach the remote host

and for the response from the host to

return.

• Asterisk (*) is used to indicate a lost

packet.

7.4 Chapter Summary

Conclusion

Chapter 7: IP Addressing

Explain the use of IPv4 addresses to provide connectivity in small to

medium-sized business networks

Configure IPv6 addresses to provide connectivity in small to

medium-sized business networks.

Use common testing utilities to verify and test network connectivity.

Chapter 7: IP Addressingvapenik.s.cnl.sk/pcsiete/CCNA1/07_IP_Addressing.pdf · Cisco Confidential 2...

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